All you gotta do is, go out in the “wild”, dig about 1 1/2 - 2 feet away from ANY tree. The soil contains 75 - 90% of needed microbial life. You can also make your own LAB. Do take care, stay EXTRA safe and, indeed, be well…mister
As the helpful @misterbee stated, going straight from the ground is always an option. Very rich in microbial life. Brewing a tea is one of the best options available honestly.
Got a sample of a soil conditioner called Fish Shit, haven’t run them as we use organic amendments that already help with microbial life in our soil. I could send you a bottle no skin off my back, give it a whirl
It is literally teeming with microbial life - as to which ones, I’m not sure. The one thing to keep in mind is that the microbial life is basically food for other life in your soil, they battle it out consuming each other and nutrients available in the soil to live and then die. When the microbes die or poop the nutrients they used in the process become ionic (ready to be digested by the plant) as why most organic soil mixes need to “bake”, this provides time for them to do their job and make more ionic nutrient. This is grossly simplified but should help you on your quest basically you are trying to breed aggressive but beneficial microbes which often takes throwing a variety of them in there and they will figure out who colonizes the substrate